One thing that I have a hard time keeping track of is which fishes are currently okay to eat. I never know what species are threatened, or which fish should be eaten from farms but not from the wild, or whatever. I'm not a fishmongerer or a chef, so it's not a crippling ignorance, but I still know that I could know more. Good published a transparency a little bit ago that shows which fishes are acceptable to eat - for me, the visual really helps my brain process the information.
I do understand that dolphins are off-limits, whether they're farmed or wild. Yikes.